In Europe, Middle East, Africa and Southeast Asia, broadcasters are looking to the DVB-T2 standard to upgrade from analog transmission, their current DVB-T implementation, or as a supplemental network. Similarly, in South America, ISDB-T is being implemented. These and other standards rely more and more on single frequency networks (SFN) to efficiently utilize wireless frequency spectrum. SFNs require synchronization so for each instant of time, every transmission station is broadcasting the same digital data at the same exact frequency.